The invention pertains to coupling systems usable to transfer materials from one flow conduit to another. More particularly, the invention pertains to two-part coupling members with a first part including a pre-slit septum and a second part including a blunt cannula. The pre-slit septum slidably receives the blunt cannula to effect the coupling.
Injection sites usable with pointed cannulae have long been known. For example, such sites can be formed with a housing having a fluid flow path therein. A septum is positioned in the housing closing the fluid flow path.
One injection site usable with a piercing cannula is disclosed in U.S. Pat. No. 4,412,573 to Zdeb entitled xe2x80x9cInjection Site.xe2x80x9d The Zdeb patent is assigned to the assignee of the present invention.
The pointed cannula can be forced through the septum into fluid flow communication with the flow path in the housing. Known injection sites usable with a piercing cannula can be physically damaged by repetitive piercing caused by the sharp cannula. This damage, known as coring or laceration, can result in subsequent leakage.
Due to problems associated with infectious agents, personnel using such pointed cannulae do so with great care. Notwithstanding careful and prudent practice, from time to time, accidents do occur and individuals using such pointed cannulae jab themselves.
Injection sites usable with a blunt cannula are also known. For example, U.S. Pat. No. 4,197,848 issued to Garrett et al. entitled xe2x80x9cClosed Urinary Irrigation Sitexe2x80x9d and assigned to the assignee of the present invention discloses one such injection site. That injection site is a relatively low pressure device having a relatively thin, molded, sealing member. The sealing member has an opening therethrough.
A blunt cannulae can be forced through the sealing member placing the cannulae into fluid flow communication with a fluid flow pathway in the injection site.
Injection sites of the type noted above usable with a blunt cannula have the advantage that the blunt cannula will not pierce the skin of a user. On the other hand, it is important that the pre-slit injection site reseal with enough force that fluids do not ooze therefrom and that airborne particulate matter, bacterial or viral matter do not enter therethrough.
Hence, there continues to be a need for a pre-slit injection site which can be used with a variety of solutions and over a range of fluid pressures. Further, there continues to be a need for such a pre-slit injection site which will reliably reseal even after many insertions of the blunt cannula.
Such an injection site should be able to receive a large number of insertions of the cannula without displaying reseal failure. Such an injection site should provide for improved alignment of the cannula on insertion. Improved alignment will result in less chance of damage to the injection site after repeated insertions of the cannula. Preferably, the injection site would also be usable with a pointed cannula. Preferably, a pre-slit injection site usable with a blunt cannula will provide a reasonable level of insertion force such that health care personnel will readily be able to insert the blunt cannula, yet the cannula will not easily fall from or drop out of contact with the septum.
In accordance with the invention, an easily wipeable injection site usable with a blunt cannula is provided. The injection site includes a housing which defines a fluid flow channel therethrough. The housing has a first and a second end.
A flexible sealing member is carried by the housing for sealing the first end. The sealing member has a resealable opening therein. The sealing member also is formed with a curved exterior peripheral surface such that the blunt cannula can be sealingly inserted through the opening and placed in fluid flow communication with the flow path. Further, the blunt cannula can be removed from the opening with the sealing member then interacting with the housing so as to reseal the opening.
The housing can also be formed with the first end including an annular channel underlying the sealing member. The sealing member is subjected to radially directed forces by a tapered surface of the first end of the housing. These forces tend to reseal the opening in the sealing member.
The sealing member can be a cylindrically shaped rubber member. The first end of the housing can include an interior tapered surface for receiving the sealing member and for applying the radially directed forces to the sealing member.
A retaining member carried by the first end of the housing can be used to retain the sealing member within the housing. The retaining member can be generally U-shaped. Alternately, the retaining member can be formed as a coiled spring.
The retaining member applies axially directed forces to the sealing member. In one embodiment of the invention, the retaining member deflects the sealing member and forms a curved exterior peripheral surface thereon. The curved exterior peripheral surface is an easily wipeable surface.
The retaining member deflects or distorts the upper and lower peripheral edges slightly as a result of applying axial forces thereto. When the blunt cannula is inserted into the slit in the sealing member, an annular interior peripheral region of the sealing member deforms further and fills, at least in part, the annular channel.
Deformation of this annular peripheral region results in an insertion force in a range of 2.0 to 5 pounds. Preferably, the insertion force will have a value of the order of 2.0 pounds.
The resealable opening in the sealing member can extend entirely through that member. Alternately, the resealable opening can extend only partway therethrough. In this embodiment, the end of the blunt cannula will be used to tear through the remainder of the sealing member.
The sealing member can be formed in two parts. An exterior cylindrical portion can be slit completely. An interior cylindrical unslit portion can be provided to seal the site until the blunt cannula is inserted therethrough the first time.
The interior surface of the first end can be formed with the taper in a range on the order of 5 degrees to 20 degrees. Preferably, the interior surface will have a taper on the order of 12 degrees. This tapered surface permits the use of a cylindrically shaped sealing member.
To provide for leak-free insertion, the length of the slit in the sealing member must be less than one-half the circumference of the cannula being inserted therethrough. Hence, the slit length may exceed the diameter of the cannula being inserted. In addition, the slit length must be great enough, given the elastic limit of the sealing member, to prevent tearing during insertion.
Further in accordance with the invention, a coupling system for coupling first and second fluid flow members together is provided. The coupling system includes an injection site which is affixed to the first fluid flow member. The injection site includes a housing. The housing has a fluid flow path therethrough.
A sealing member is carried by the housing. The sealing member has a resealable opening therein.
An annular retaining member is carried by the housing and cooperates with the housing to retain the sealing member therein. Radially directed forces are applied to the sealing member by the housing, thereby urging the opening into a resealed condition.
A blunt cannula, affixed to second fluid flow member, has a fluid flow path therethrough. The cannula carries a locking member for lockingly engaging the housing when the cannula extends through the opening of the sealing member. When so positioned, the two fluid flow members are placed into fluid flow communication.
The locking member can include a luer-type twist lock fitting. Alternately, the locking member can include slidably engageable members which are responsive to axial movement of the injection site and the cannula toward one another.
In accordance with further aspects of this invention, the blunt cannula may be provided with features that facilitate insertion into the injection site, enhance fluid flow or dispersion, increase tug resistance, and reduce kickback.
In particular, one embodiment of the cannula includes a tube with a plurality of elongate discharge slots adjacent the distal end. The fluid changes direction as it passes laterally through the slots and out of the tube. The flow area of the slots exceeds the flow area inside the tube. This slot structure enhances fluid flow and dispersion characteristics. In addition, the slots decrease the contact surface area on the tube exterior so as to facilitate insertion.
In a further modification, the cannula includes a lead post on the tube distal end to guide the cannula through the slit in the injection site.
In another cannula embodiment, the tube is generally cylindrical and the fluid discharges directly from an open end of the tube. The exterior surface of the tube is provided with grooves to reduce the contact surface area.
In still another cannula embodiment, the tube has a cylindrical portion and a tapered distal end portion which are each about equal in length. The taper facilitates insertion, and the remaining cylindrical portion reduces kickback.
In yet another embodiment, the cannula includes an annular barb which functions to reduce kickback.
Other advantages of a blunt plastic cannula in accordance with the invention, relative to conventional steel needles include a higher fluid flow rate capacity and a simpler one-piece plastic design.